Some of the nutrients we think of as "found only in plants" really aren't. Sea mammal blubber (fat from whale and seals), is reported to be exceptionally high in Vitamin C (with more vitamin C per kilo than oranges).

The opposite is also true in that people associate certain nutrients to meat those nutrients are also found in plants. My mind immediately jumped to scurvy as it was a common disease hundreds of years ago with sailors and pirates who went for long periods of time without access to plants.

I also am aware of the studies on the Inuit and although their plant sources are limited I remember reading that their diet wasn't just meat.